Arcadis NV — M&A Activity 2011

May 17, 2011

ARCADIS NV Gustav Mahlerplein 97-103 P.O. Box 7895 1008 AB Amsterdam The Netherlands Tel +31 20 2011 011 www.arcadis.com

PRESS RELEASE

ARCADIS EXPANDS IN BRAZIL BY ACQUIRING REMAINDER OF ARCADIS LOGOS

May 17, 2011 – ARCADIS (EURONEXT: ARCAD), the international consultancy, design, engineering and management services company, today announced that it is expanding its position in Brazil by purchasing the remaining shares in ARCADIS Logos in which the company already holds 50% plus 1 share. An agreement has been signed to acquire the remaining shares held by Logos Holding, a partnership of 24 partners of whom 13 are still active in the business. The agreement concerns the project management, consultancy, engineering and environmental activities of ARCADIS Logos which are core business to ARCADIS. The energy producing assets of ARCADIS Logos, consisting of Biogas installations and small hydropower plants, are not part of the deal. These assets are currently being sold and income from (the sale of) these assets will be distributed according to the current joint shareholding.

ARCADIS entered the Brazilian market in 1999 by acquiring 50% plus 1 share in Logos Ltda, a leading project management consulting company in Brazil, which was later renamed ARCADIS Logos. The company has developed very successfully, from about 200 people in 1999 to more than 2100 people today, partly through small acquisitions, adding engineering and environmental capabilities. Gross revenues of the business in which ARCADIS will have a 100% ownership is expected to be over € 150 million in 2011, with margins well above the ARCADIS average. Backlog is very strong and provides a solid basis for continued strong growth in the Brazilian market which is expected to benefit from large investments related to modernization of infrastructure and the 2016 Olympic games in Rio de Janeiro.

The purchase price for the remaining shares is based on ARCADIS' usual valuation approach. In addition to a cash payment, the transaction will be partly financed by issuing 1.16 million ARCADIS NV shares to the Logos Holding partners. These shares will have a lock up period of 6 months with incentives for the active partners to hold them for at least 18 months after closing. As ARCADIS Logos is already fully consolidated in the ARCADIS accounts, the transaction will not impact revenues and EBITA, but it will have a positive effect on net income from operations. The transaction is expected to close in July 2011 and will be immediately accretive to earnings per share (based on net income from operations which excludes amortization). Further financial details were not disclosed.

ARCADIS CEO Harrie Noy: "I am very proud that we are able to further expand in the rapidly growing Brazilian market through a company we know well and respect for their quality and dedication to clients and growth. The Logos Holding partners are making a clear choice for the company's future growth by turning their shares over to ARCADIS at this crucial time in the company's development. With this step we are even better positioned to

benefit from the favorable market climate in Brazil, which is fueled by a strong economy and the 2016 Olympic games."

Manoel Antonio Amarante Avelino da Silva, CEO of ARCADIS Logos, added: "Capitalizing on the current growth opportunities in the Brazilian market, was hampered by the partnership structure. Therefore the partners of Logos Holding approached ARCADIS with the proposal for this transaction. Our longstanding relationship with ARCADIS, based on mutual trust, has worked out very well over the past twelve years for all parties involved. In the new situation we can offer more opportunities to our staff and we are able to grow our business more rapidly, using the financial strength of ARCADIS and capturing on synergies."

For more information, please contact Joost Slooten of ARCADIS at +31-202011083 or outside office hours at +31-627061880 or e-mail joost.slooten@arcadis.com

About ARCADIS:

ARCADIS is an international company providing consultancy, design, engineering and management services in infrastructure, water, environment and buildings. We enhance mobility, sustainability and quality of life by creating balance in the built and natural environment. ARCADIS develops, designs, implements, maintains and operates projects for companies and governments. With 16,000 employees and over € 2 billion in revenues, the company has an extensive international network supported by strong local market positions. ARCADIS supports UN-HABITAT with knowledge and expertise to improve the quality of life in rapidly growing cities around the world. Visit us at: www.arcadis.com.